Remove dead HistorianStore Protocol, reset query.completed to v1, add HTTP batch/search tests

[randileeharper]

Summary

Three issues bundled together — all are small, self-contained cleanup items.

Issue #25 — Delete dead HistorianStore Protocol

The HistorianStore Protocol in storage.py was never used as a type annotation anywhere. HistorianService and AppContext both reference SQLiteHistorianStore directly. The Protocol signatures had also drifted from the concrete class (wrong search/get_event params, missing ~9 methods). Removed the Protocol class and the now-unused Protocol import.

Issue #31 — Reset historian.query.completed to version 1

historian.query.completed was registered at version 2 in builtin_manifest.json with no version 1 ever existing. All other builtin schemas use version 1. Reset the manifest to "version": 1 and updated "schemaversion": 2 → "1" in service.py _record_query to match.

Issue #32 — Add HTTP batch and search endpoint tests

No test coverage existed for POST /v1/events:batch or POST /v1/search. Added four tests in tests/test_http.py:

Test	What it covers
test_batch_endpoint_ingests_valid_batch	Valid batch through POST /v1/events:batch — response shape, event IDs, duplicate flags
test_batch_endpoint_rejects_missing_events_array	Malformed body (no events array) → 422
test_search_endpoint_filters_by_fields	POST /v1/search with apps/exact_phrases/limit — returns only matching events
test_search_endpoint_rejects_invalid_spec	Invalid search fields → 422

Closes #25, closes #31, closes #32.

Test commands run

uv run pytest -q
uv run python -m compileall historian tests

All 88 tests pass (4 new); compile check clean.